Two good sources for me to learn about nice concepts of the Haskell language have been http://learnyouahaskell.com/ and http://www.realworldhaskell.org/blog/ both of which you can use online and for free .) - I hope they can give you some nice steps further. Even when they don't teach the most advanced concepts, they may give you a pretty good insight into what is there and what it might be usefull for.
